Lithium—a simple metal and the oldest drug in psychiatry—might protect the brain against mental illness, Alzheimer’s, and other diseases. One problem: There’s no profit in it.

Lithium is as puzzling as it is potent. It was the first drug used to treat mental illness, and more than 50 years later, it is still one of the most widely used psychiatric medications. But the doctors who prescribe lithium to their patients still do not know how it works or even why it works. “It is the most mysterious drug in psychiatry,” says De-Maw Chuang, a biologist at the National Institute of Mental Health. “It’s so small, but it is so powerful.”
Unlike oth...

The full text of this article is available to Discover Magazine subscribers only.